This Phase I project aims specifically to demonstrate the feasibility of developing inexpensive reagents to affinity purify recombinant DNA molecules. The methodology, once developed, will be directed to the problem of chromosome purification. During the Phase I period, the applicants will use X chromosome alpha satellite specific sequences to serve as a model for reagent development. Initially, the plan is to test the feasibility of developing reagents to: (1) form triplexes with human chromosome specific centromeric sequences, (2) form triplexes with third strands covalently modified with specific ligands, and (3) to immobilize the specific third strand forming oligonucleotides to solid supports in order to develop affinity purification procedures. Although the overall goal of the project is to develop reagents for chromosome purification, it is expected that after the development of such technology, it could be utilized for the affinity purification of recombinant DNA cloned into plasmids, YACs (yeast artificial chromosomes), phages (lambda and Pl), and cosmids.